The objective of the proposed research is to provide a more thorough understanding of the PZ-peptidases from mammalian spermatozoa and testes with respect to the subcellular localization, biochemical properties and physiological function of these enzymes. The subcellular location of the PZ-peptidase in spermatozoa will be determined by immunocytochemical techniques, using antibodies raised against a highly purified PZ-peptidase isolated from testes. The PZ-peptidase from bovine testicular tissue and spermatozoa will be purified to homogeneity by employing a combination of classical and bio-specific fractionation procedures. The biochemical properties of the PZ-peptidase, including susceptibility to inhibitors, requirement for activators and stabilizers, and substrate specificity toward native proteins, peptides and synthetic substrates, will be examined using the purified enzyme preparations. Investigations into the physiological function of the PZ-peptidase will examine the possible involvement of the enzyme in the reproductive processes relating to sperm penetration of the ovum investments, activation of spermatozoal proenzymes, control of sperm motility through regulation of kinins and other events associated with fertilization. The proline carboxypeptidase from spermatozoa and testes will also be purified and biochemically characterized in order to determine its possible role in reproductive functions. It is anticipated that the information obtained as a result of these studies may find application in the fields of reproductive biology and fertility regulation.